%绘制函数图像
% x=-2:0.01:2;
% y=1./x;
% plot(0,0,'.','MarkerSize',10);
% hold on;
% plot(x,y,'b');
% saveas(gcf,'c1_10.png');
[X,Y,Z] = peaks;
contour(X,Y,Z,'LevelList',[0]);